Muramidase

Abstract: The distribution of muramidase (lysozyme) in normal and pathological human tissues has been studied, using an immunohistological technique. The enzyme was demonstrated in a variety of healthy tissues, including serous salivary acinar cells, lactating mammary tissue, Paneth cells, renal tubular cells, myeloid cells (including eosinophils), and histiocytic cells. In pathological tissues the most striking positivity was encountered in reactive histiocytic cells in granulomatous conditions such as tuberculosis and Crohn's disease. The finding of this study are related to previous reports of the distribution of human and animal muramidase and the implications of patterns of muramidase staining in pathological histiocytes are briefly discussed.

Abstract: Since the discovery of lysozyme by Fleming (1922) several authors have proposed different methods for determining the activity of various preparations containing this enzyme. Most of these methods were based upon the clearing of dense suspensions of a susceptible organism without concern for accurate quantitative results. The isolation of highly purified crystalline lysozyme by Alderton and Fevold (1946) suggested the possibility of a method for assaying lysozyme. The procedure described here provides for the rapid and accurate microbiological assay of materials that show lytic activity considered to be due to lysozyme. Fleming (1922), in his original work, observed the lytic activity of lysozyme either as clear zones on agar plates seeded with Micrococcus lysodeikticus or as a clearing of a suspension of the same organism. Sandow (1926) used serial dilutions of egg white in meat infusion broth inoculated with various species of organisms. After incubation these mixtures were observed for growth, as evidenced by the turbidity of the tubes. This procedure was applied to a study of the different organisms affected by lysozyme, the dilution of egg white capable of producing inhibition or sterilization being noted. Goldsworthy and Florey (1930) devised a scheme of assay which consisted of washing an 18-hour culture of M. lysodeikticus with saline and adjusting the opacity of that suspension to that of Brown's barium sulfate standard no. 4. Lysozyme was serially diluted so that each succeeding dilution contained only half as much of the enzyme as the one previous. Then 0.5 ml of each dilution was mixed with an equal quantity of cell suspension. The mixtures were allowed to incubate at 38 C for 1 hour. A unit was defined as the least amount of lysozyme necessary to produce complete lysis. Rosenthal and Lieberman (1931) in determining the lysozyme content of infant stools mixed a susceptible sarcina with stool extracts. Visual observations of the mixture were made under the microscope. A disappearance of the sarcina cells indicated lysozyme activity. Boasson (1938) developed a technique involving the use of optical measurements of turbidity. A phenol-killed suspension of the test organism was mixed with various dilutions of lysozyme. The amount and rate of clearing was carefully measured in a Moll extinctometer and correlated with the concentration of lysozyme. Since the activity for the known concentration could be observed accurately, it was possible to compare the extent of activity of an unknown and in this manner to determine the amount of lysozyme present.